This invention relates to a wafer supporting jig and a decompressed gas phase method using such a jig for evenly growing a nitride film (Si.sub.3 N.sub.4), a low temperature oxide film (LTO), a high temperature oxide film (HTO), a phosphor glass (PSG) film, a boron phosphor glass (BPSG) film, a refractory metal film, a metal silicide film, a Si--Ge epitaxial growth film or a III-V or II-IV group epitaxial growth film on a substrate wafer to be used for a semiconductor device.
Decompressed gas phase growth apparatus are popularly used in the semiconductor manufacturing industry for growing oxide or nitride films on substrate wafers. Such known apparatus are generally categorized into two groups; a horizontal type apparatus as illustrated in FIG. 14 which comprises a horizontally arranged oblong reaction tube 1 surrounded by a heater 2, wherein a number of wafers 3 are vertically arranged on so many wafer boats 4 and gas flows in the tube as it is introduced from the gas inlet port 5 of a flange connected with said reactor tube and and ejected from the outlet port 6 and a vertical type apparatus as illustrated in FIG. 15 which comprises a vertically arranged reactor tube 1' surrounded by a heater 2', wherein a number of substrate wafers 3' are horizontally arranged on so many wafer boats 4' and gas flows in the tube as it is introduced from the gas inlet port 5' located at the upper or lower end of the reaction tube and ejected from the outlet port 6'. The method of growing oxide and/or nitride films by using silane gas (SiH.sub.4) in these known gas phase growth apparatus is accompanied by the drawback of producing wafers with too thick edge portions and the difficulty with which evenly thick films are formed. In order to bypass these drawbacks, boats are usually realized in the form of cylinders provided with a large number of bores, each boat (which is popularly called a gage boat according to the well-known trade name) is formed by two halves which can be separated for ease of introducing and taking out wafers by using a pair of pincers. However, the above described known method obviously lacks efficiency and deters the way for automation. Moreover, the method is accompanied by the problem of introducing dirt when the boat is opened, which eventually sticks to the wafers.